So I used the "Universal Widescreen Patcher" to change the resolution to 1920x1080, but after using that res the the intro movie doesn't play properly, as in the sound works but the screen is just black. Any idea how to fix this?

Personally I'd suggest using this: http://www.wsgf.org/article/star-wars-knights-old-republic

This way you don't need to run that injecting program in the background, this will modify your exe to allow widescreen. It also has links to files you put in your override directory for stuff like cut scenes.

Check out my post here in the Widescreen stickied thread and see if this gets you up and running:

http://www.gog.com/forum/star_wars_knights_of_the_old_republic/widescreen/post25